Amorphous alloys have a combination of high strength, elasticity, corrosion resistance and processability from the molten state. Amorphous alloys are generally processed and formed by cooling a molten alloy from above the melting temperature of the crystalline phase (or the thermodynamic melting temperature) to below the “glass transition temperature” of the amorphous phase at “sufficiently fast” cooling rates, such that the nucleation and growth of alloy crystals is avoided. As such, the processing methods for amorphous alloys have always been concerned with quantifying the “sufficiently fast cooling rate”, which is also referred to as “critical cooling rate”, to ensure formation of the amorphous phase.
Conventional processes have not been suitable for forming amorphous alloys, and special casting processes such as melt spinning and planar flow casting are often used. For crystalline alloys having fast crystallization kinetics, extremely short times (on the order of 10−3 seconds or less) for heat extraction from the molten alloy are used to bypass crystallization. Such amorphous alloys are capable of forming only very thin amorphous foils and ribbons (order of 25 microns in thickness).
However, difficulties are still encountered during casting and molding of bulk metallic glasses (“BMGs”). As such, there is still a need for improved casting and molding techniques associated with BMGs.